A botulism outbreak killed nearly 3,000 ducks and other birds in Nevada in 2011, the ninth deadliest year on record.

But the Reno Gazette-Journal (http://on.rgj.com/PBqxhv ) reports that with the exception of some isolated incidents, such outbreaks this year have been scarce - so far.

Avian botulism is not considered a threat to humans. It becomes prevalent when water levels drop, exposing toxins present in the soil. Birds either ingest the toxins directly, or eat infected invertebrate like fly larvae.

The 2012 drought has led to stagnant water and favorable conditions for disease. But officials say so far there's no evidence of a widespread outbreak.

The waterfowl hunting season opens Oct. 13.

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